Remove the notion of dies at entry.

- Instead, explicitly say that the output does not overlap.
- Inputs that must be in a fixed register do die at entry,
  as we know they have a location that others can not take.
- There is also no need to differentiate between an input move
  and a connecting sibling move - those can be put in the
  same parallel move instruction.

Change-Id: I1b2b2827906601f822b59fb9d6a21d48e43bae27